Top 5 Reasons for Using ECTFE (Halar®) in Corrosive Environments

Ethyelene Chlorotrifluoroethylene, marketed and sold under the trademark name Halar® ECTFE, is a fluorinated plastic. Developed for chemical resistance in corrosive applications and introduced in 1970, this polymer is used in many industries requiring resistance to corrosion. Here are the top 5 reasons why!

1) Physical and Chemical Properties

ECTFE has an operating range of -105 °F to 300 °F and has good fire resistance. It is resistant to both acids and bases (from 1 to 14 pH). It has great impact strength and stiffness, allowing its use in pressure piping systems. Other notable physical properties include excellent abrasion resistance and weathering resistance. Table 1 presents a summary of the polymer’s physical properties for some of the common forms in which it is commercially available.

Table 1*

Foamable Grade for Wire Coating

Pellets for Sheet Extrusion and Compression Molding

Food Grade (FDA Approved)

Tensile Strength (psi)

6,800

6,800

7,800

Elongation (%)

250

250

250

Elastic Modulus (ksi)

240

240

240

Density (g/cm3)

1.68

1.68

1.68

Impact Resistance (ft·lbf/in)

50

65

105

Melting Point (°F)

468

436

468

*Based on data from http://www.solvayplastics.com

2) Electrical and UV Properties

ECTFE is a good electrical insulator with high resistivity, a low dielectric constant, and a low dissipation factor (see Table 2). These properties make ECTFE useful in the electronics industry as cable jackets (a coating or covering). The polymer also has good UV resistance, making it suitable for outdoor applications.

Table 2*

Foamable Grade for Wire Coating

Pellets for Sheet Extrusion and Compression Molding

Food Grade (FDA Approved)

Volume Resistivity (Ω·inch)

2.16·1016

Dielectric Strength (V/mil)

350

Dielectric Constant

240

*Based on data from http://www.solvayplastics.com

3) Weldability and Machinability

Another benefit of this plastic is weldability. Resistance, infrared, hot gas, ultrasonic, and high frequency welding are all possible with this polymer. ECTFE also has excellent machinability, allowing for easier fabrication of plastic components.

4) Industrial Uses

With its excellent corrosion resistance, physical properties, electrical properties, UV resistance, and weldability, ECTFE has been used with success in the following applications:

Bleaching towers in paper mills.

Production, transfer, and storage of sulfuric acids. For example, in Denmark ECTFE was used to line the interior of a chimney at a power station. Over a period of 15 years, the chimney lining was continually exposed to sulfuric acid at 230 °F. A recent inspection indicated no signs of chemical degradation or cracking.

Transport vessels for hazardous materials.

Clean room ductwork. ECTFE can be produced or deposited to create a very smooth coating. This coating is used to line ductwork in clean rooms. The high smoothness minimizes the risk of pinholes in the coating. It also deters the accumulation of particles along the walls of the ductwork.

Chemical storage tanks and transfer pipes in the semiconductor industry and energy industry. For example, in one application at a petrochemical plant, a chlorine scrubber (pollution removal device) was coated in part with ECTFE. For 14 years, the scrubber was continually exposed to hydrochloric acid and chlorine gas. After inspection, the liner was found to be in excellent condition. In another example, a chemical holding tank at a plastics production plant was lined with ECTFE. The holding tank was in service for 23 years, continually used to store alkaline-based materials and chlorine. Inspection revealed no chemical degradation of the lining.

5) Solid Structures and Coatings

ECTFE can be produced as solid structures (like pipes or sheets) or applied as a coating or a liner. Solid components can be produced using injection molding, extrusion, and blow molding. Coatings can be applied to metal using electrostatic powder coating. Alternatively, a sheet of it can be applied mechanically. In other cases, it is applied as a film with an appropriate coating.

Conclusion

Based on ECTFE’s superior corrosion resistance, and its good physical and electrical properties, it is the product of choice in industries that use, handle, and store corrosive chemicals.